What happened to Lion Air flight JT610?
Voice recorder from crashed plane found under eight metres of mud
Indonesian salvage divers have located the second so-called black box from a Lion Air flight that crashed into the Java Sea in October, killing all 189 people on board.
Authorities in Indonesia confirmed on Monday that human remains were also found alongside the cockpit voice recorder (CVR), reports CNN.
The discovery of the CVR is expected to end months of speculation about what happened to Lion Air flight 610 before it went down on 29 October 2018. The two-month-old Boeing 737 MAX 8 plunged into the sea just minutes after taking off from nearby Jakarta.
The box was found buried under eight metres (26ft) of seabed mud in waters about 30 metres (98ft) deep, said Navy spokesperson Lieutenant Colonel Agung Nugroho, who added that divers had used a hi-tech “ping locator” to find the device.
“We don’t know what damage there is, it has obvious scratches on it,” Nugroho added.
The full timeline of events leading to the crash are likely to remain unclear until the contents of the CVR have been fully analysed.
But aviation authorities have already filed a preliminary report based on information retrieved from the first of the two recorders found - the flight data recorder (FDR), which stores any instructions sent to the electronic systems on the aircraft. This is separate from the CVR, which records the audio from the flight deck, including the crew’s vocal communications with each other and air traffic control.
The preliminary report revealed that following a number of faulty readings during previous flights, the aircraft’s Angle of Attack (AOA) sensor had been replaced and tested on 27 October, two days before the crash.
On 28 October, the pilot of the aircraft noticed that the AOA sensor was giving erroneous readings once again, prompting the aircraft’s new automatic safety system - the Maneuvering Characteristics Augmentation System (MCAS) - to pitch the nose of the Boeing 737-Max down to correct the perceived fault and thereby avoid putting the plane into a stall.
Data shows that the pilot turned off the “stabiliser trim switches” that were causing the plane to auto-correct its AOA and reported the issue upon landing - although a statement from the aircraft’s manufacturer, Boeing, suggests that the extent to which this was flagged by the pilot as a major fault is unclear.
The flight data recorder from the flight that would crash the following day showed that, again, the AOA had given faulty readings, causing the nose to repeatedly pitch down. However, the stabiliser trim switches were not turned off, leaving the pilots struggling, unsuccessfully, to keep the plane under control.
The analysis of the CVR is expected to reveal what the pilots were saying during those final minutes, and why the safety feature was not turned off. The information is expected to be downloaded from the box by Indonesian authorities today.
In mid-November, two weeks after the crash, a formal complaint was filed by a Florida-based law firm on behalf of the parents of Rio Nanda Pratama, a doctor who was on the flight.
The lawsuit says that "under certain conditions [MCAS] can push the nose down unexpectedly and so strongly that the pilot cannot pull it back up in time to avoid a crash”, and that the feature “can be triggered even if pilots are manually flying the aircraft and don't expect flight-control computers to kick in”.
The suit adds: “It is particularly surprising to hear from safety experts and the heads of pilots' unions that Boeing failed to warn its customers and the pilots of its new 737 Max aircraft about this significant change in the flight-control systems.”
Boeing said in a statement that it could not comment on ongoing investigations, but that a safety bulletin had been issued reminding pilots how to handle incorrect data provided by the AOA sensor.
The firm added that it was “confident in the safety of the 737-Max”.